Road finishers or asphalt finishers are construction machines used for producing asphalt surfaces. These construction machines are as well referred to as so-called pavers, especially wheel or track pavers. To this end, the road finisher distributes and smoothes bituminous paving material, and depending on the embodiment, also compacts the same. Such a road finisher is disclosed, for example, in WO 2009/095146 A1, the disclosure of which is incorporated herein by reference. Essential components of a generic road finisher are a bunker for the accommodation of the paving material, a transport unit, by means of which the paving material is transported to the paving site, a distributing device, by means of which the paving material is distributed across the width of the area to be paved, and a so-called paving screed, by means of which the ejected paving material is smoothed to obtain a homogeneous surface. The paving screed may include a number of functional units. Thus, apart from a screed plate that smoothes the paving material, the paving screed also frequently comprises a so-called tamper bar that performs the task, for example, of pre-compacting the paving material before it is smoothed down by the screed plate. The problem to be solved when laying paving materials is that of preventing, or at least reducing, the occurrence of sticking of the bituminous mixture to the respective paving devices as far as possible. To enlarge the paving screed, extendable screed extensions can be applied on both sides.
For this purpose, it is known from the prior art to heat particularly those contact surfaces of the tamper bar and/or the screed plate that are oriented towards the paving material. In addition to gas-powered heating devices, it has also proved to be particularly advantageous to use an electrical heating device for this purpose. Such an electrical heating device is frequently located in appropriate cavities inside the tamper bar and/or the screed plate, for example, in the form of a bar-shaped heating element, as specifically disclosed in WO 2009/095146 A1. The electrical heating device described therein is, however, relatively expensive in terms of production and maintenance. Furthermore, the obtained air gap results in inefficient heat transfer and a relatively long reaction time during the heating process. EP 1 416 090 A2 teaches adhesive bonding of heating elements to the paving screed. However, under the environmental conditions during operation, the organic materials used are apt to disintegrate and to release hazardous decomposition products. In addition, this arrangement requires a complex manual assembling procedure. Finally, the heating arrangement obtained is only of low mechanical resistance, and the heat transfer from the heating element to the screed plate is impaired by the used adhesives, so that, for example, the heating phase of the screed plate is still relatively long.
It is thus an object of the present invention to provide a road finisher, a screed plate, and a tamper bar that comprise an electrical heating device having an optimized construction while at the same time making it possible, in particular, to effect heating faster and more uniformly than heating devices known hitherto in the art.